This invention relates to anchor systems for joining structural members, methods of making and using those systems and combinations of structural parts joined by the anchor systems. More particularly, the invention relates to tensioned anchor systems that give an indication that the system is under the appropriate tension, mold parts used to adapt poured concrete structural members for use with the anchor systems and joined structural members, such as columns and road barriers, employing the anchoring systems of the invention.
Threaded anchors that are secured with a securing agent in a hole into which the anchor is inserted are well known. In an improved anchoring system a fast setting polymer resin is introduced into the hole to fill the bottom portion of the hole, and a significantly slower setting resin securing agent fills the remaining upper portion of the hole. Then, once the faster setting securing agent has set, the anchor is tensioned by turning down a retaining nut on the exterior end. The torque induced tension to which the anchor is drawn is calculated to be higher than any subsequent forces the anchor will subsequently receive when loaded. The tension is maintained in the anchor portion extending from the quick-setting securing agent to the nut as the slower setting securing agent hardens. The load transfer via the resins to the surrounding concrete structure is accomplished on a molecularly bonded radially distributed basis over the height of the now adhesively secured, strained steel anchor. The bonded, extended anchor thus has its torquing energy distributed to the concrete causing compression within the structure. The stored energy in these systems is available to react to subsequent loads. The molecular bonding provides much more efficient load transfer than a mere mechanical action from commonly used non-shrink cementitious grouts.
In the improved systems as just described it was not evident if subsequently the anchor had loosened, for example, by elongation due to creep. Nor was there a means for continuing to apply tension to an elongated anchor member.
Structural members such as columns supporting bridges or freeways have utilized adjoining openings between which extend an anchor member that may have been grouted in at least one of the openings, but that was itself passive or free of loading. During earthquakes, these joined structural members have been known to fail at such junctions. Typically the rebars joining the members are not pre-loaded, nor bonded to the concrete. Thus, they have very little capacity to resist enormous multi-directed lateral and vertical seismic forces.
A means for quickly readily forming a structural member to accept chemically secured-in-place anchors without leaving behind a residue of release agent in the freshly poured concrete has been needed to assure that a liquid securing agent introduced into a hole molded in the concrete had purchase on the interior surface of the hole and readily transfer loads on a molecular basis by virtue of the bond anchor and the concrete. Known hole firming devices have acted as bond breakers to the concrete. The result has been mechanical load transfer from the anchor to the concrete rather than load transfer at a molecular level.
Road barriers have been joined end-to-end in the past, but have not been readily adapted for the introduction of grout into anchor receiving openings, and they have not been joined end-to-end with an anchor especially adapted to permit their being situated at an angle other than 180.degree..